7.2.1 Invoking grotty

Use overprint and disable colours for printing on legacy Teletype
printers (see below).

-d

Do not render lines (this is, ignore all \D escapes).

-f

Use form feed control characters in the output.

-Fdir

Put the directory dir/devname in front of the
search path for the font and device description files, given the
target device name.

-h

Use horizontal tabs for sequences of 8 space characters.

-i

Request italic glyphs from the terminal. Ignored if -c is
active.

-o

Do not overstrike.

-r

Highlight italic glyphs. Ignored if -c is active.

-u

Do not underline italic glyphs. Ignored if -c isn’t used.

-U

Do not overstrike bold-italic glyphs. Ignored if -c isn’t
used.

-v

Print the version number.

The -c mode for TTY output devices means that underlining is
done by emitting sequences of ‘_’ and ‘^H’ (the backspace
character) before the actual character. Literally, this is printing
an underline character, then moving the caret back one character
position, and printing the actual character at the same position as
the underline character (similar to a typewriter). Usually, a modern
terminal can’t interpret this (and the original Teletype machines for
which this sequence was appropriate are no longer in use). You need
a pager program like less that translates this into
ISO 6429 SGR sequences to control terminals.